linux-kernel - Re: [git pull] vfs pile 1

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Message-ID: <20140129133714.GE8749@quack.suse.cz>
Date:	Wed, 29 Jan 2014 14:37:14 +0100
From:	Jan Kara <jack@...e.cz>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Al Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
	Christoph Hellwig <hch@....de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Jaegeuk Kim <jaegeuk.kim@...sung.com>
Subject: Re: [git pull] vfs pile 1

On Tue 28-01-14 19:26:08, Linus Torvalds wrote:
> On Mon, Jan 27, 2014 at 6:25 AM, Al Viro <viro@...iv.linux.org.uk> wrote:
> >         Assorted stuff; the biggest pile here is Christoph's ACL series.
> > Plus assorted cleanups and fixes all over the place...  There will be
> > another pile later this week.
> 
> The posix_acl_chmod() code looks wrong.
> 
> Not that it looked right before either, but whatever. The code
> basically looks like some variation of this in most setattr()
> implementations:
> 
>         if (ia_valid & ATTR_MODE)
>                 rc = posix_acl_chmod(inode, inode->i_mode);
> 
> but the mode we're changing to (and what ATTR_MODE guards) is actually
> attr->ia_mode, not inode->i_mode.
  Yes, but posix_acl_chmod() is called after setattr_copy() was done so
inode->i_mode should be the same as attr->ia_mode. Whether i_mode or
ia_mode is mode logical depends on whether you view posix_acl_chmod() as
"sync current i_mode into acls" or "reflect this i_mode change in acls".
I agree the function name suggests more the latter semantics.

> And quite frankly, passing in inode->i_mode looks stupid, since we're
> already passing in the inode pointer, so that's just redundant and
> pointless information.
  Yes, it looks stupid. We could almost drop that argument, except that f2fs
tries to play some tricks with i_mode and stores i_mode in a different
place when acls are enabled. Huh? Jaegeuk, can you explain why are you
doing that?

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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